1. Field of the Invention
This invention relates generally to environmental testing apparatus and associated hardware, and more specifically to an improved foam protecting purge vessel for use with analytical instruments.
2. Description of the Prior Art
One of the inherent difficulties with conducting purge and trap analysis on various environmental matrices is the problem of surfactant-laden or "foamy" samples. Foamy samples present several problems when methods call for purge and trap analysis and standard purge vessels are employed. As the foamy sample purges and the foam level reaches the top of the sparge tube, the foam is often pushed by the gas stream onto the trap, thus saturating the trap with a liquid rather than the intended gas. This effect can result in major instrument contamination, especially if the surfactant permeates the trap and enters the gas chromatograph and subsequent detectors. More importantly, from an analytical standpoint, low level or normal operating detection levels may be seldom attainable due to the number of dilutions needed to prevent the sample from foaming in the sparge vessel. If automated instrumentation is employed, subsequent samples may be highly susceptible to analytical error due to cross-contamination from the initial foamy sample. Costly and time consuming re-analysis of the sample set and decontamination of the instrumentation may then be necessary to insure the integrity of the ensuing analytical data.